WO2019054278A1

WO2019054278A1 - Eddy current-type damper

Info

Publication number: WO2019054278A1
Application number: PCT/JP2018/033061
Authority: WO
Inventors: 野口　泰隆; 今西　憲治; 亮介増井; 裕野上
Original assignee: 新日鐵住金株式会社
Priority date: 2017-09-13
Filing date: 2018-09-06
Publication date: 2019-03-21
Also published as: EP3683473A1; CN111065840A; KR20200052916A; TWI678483B; KR102338805B1; EP3683473A4; JPWO2019054278A1; US20200400211A1; TW201930747A; JP6863465B2

Abstract

This eddy current-type damper (1) is provided with: a threaded shaft (7) that is capable of moving in an axial direction; a plurality of first permanent magnets (3); a plurality of second permanent magnets (4); a magnet holding member (2) formed in a cylindrical shape; a current-conducting member (5) which is formed in a cylindrical shape and which has conductive properties; a ball nut (6) which meshes with the threaded shaft (7); and a heat transfer layer (12) which covers a surface of the current-conducting member (5) facing the first permanent magnets (3) and the second permanent magnets (4). The magnet holding member (2) holds the first permanent magnets (3) and the second permanent magnets (4). The current-conducting member (5) is disposed so as to face, across a gap, the first permanent magnets (3) and the second permanent magnets (4). The ball nut (6) is disposed inside the current-conducting member (5) and the magnet holding member (2) and is fixed to the magnet holding member (2) or the current-conducting member (5). The heat transfer layer (12) has a higher thermal conductivity than the current-conducting member (5).

Description

Eddy current damper

The present invention relates to an eddy current damper.

In order to protect a building from the vibration by an earthquake etc., a damping device is attached to a building. The damping device converts kinetic energy given to the building into other energy (eg, thermal energy). This suppresses large shaking of the building. The damping device is, for example, a damper. The types of dampers are, for example, oil type and shear resistance type. In general, oil type and shear resistance type dampers are often used in buildings. The oil type damper uses the incompressible fluid in the cylinder to damp the vibration. The shear resistance damper damps the vibration by using the shear resistance of the viscous fluid.

However, the viscosity of the viscous fluid used in particular in shear resistant dampers depends on the temperature of the viscous fluid. That is, the damping force of the shear resistance damper depends on the temperature. Therefore, when using a shear resistant damper in a building, it is necessary to select an appropriate viscous fluid in consideration of the use environment. Further, in a damper using a fluid such as an oil type or a shear resistance type, the pressure of the fluid may rise due to temperature rise and the like, and mechanical elements such as the seal material of the cylinder may be damaged. An eddy current damper is known as a damper with extremely small temperature dependence of damping force.

Conventional eddy current dampers are disclosed, for example, in Japanese Patent Publication No. 5-86496 (Patent Document 1) and Japanese Patent Application Publication No. 2000-320607 (Patent Document 2).

The eddy current damper of Patent Document 1 includes a plurality of permanent magnets attached to a main cylinder, a hysteresis member connected to a screw shaft, a ball nut meshing with the screw shaft, and a sub cylinder connected to a ball nut. Equipped with The plurality of permanent magnets alternate in the arrangement of the magnetic poles. The hysteresis material is conductive. Hereinafter, the hysteresis material is also referred to as a conductive member. The hysteresis material faces the plurality of permanent magnets and is capable of relative rotation. When kinetic energy is applied to the eddy current damper, the sub cylinder and the ball nut move in the axial direction, and the hysteresis material is rotated by the action of the ball screw. Thereby, kinetic energy is consumed by the hysteresis loss. Further, it is described in Patent Document 1 that kinetic energy is consumed by an eddy current loss because an eddy current is generated in the hysteresis material.

The eddy current damper of Patent Document 2 is attached to a guide nut that engages with a screw shaft, a drum of a conductor attached to the guide nut, a casing provided on the inner peripheral surface side of the drum, and an outer peripheral surface of the casing. And a plurality of permanent magnets opposed to the inner circumferential surface of the drum with a predetermined gap. Even if the guide nut and the drum rotate as the screw shaft advances and retracts, the inner circumferential surface of the drum and the permanent magnet do not slide because they do not contact each other. As a result, Patent Document 2 describes that the number of times of maintenance can be reduced compared to an oil type damper.

Tokuhei 5-86496 JP 2000-320607 A

In the eddy current damper of Patent Document 1, a plurality of permanent magnets are arranged along the circumferential direction. When kinetic energy is applied to the damper, the conductive member rotates in the magnetic field generated by each of the permanent magnets. At this time, eddy currents are generated in the regions of the surface of the conductive member facing the respective permanent magnets. Thereby, a damping force is applied to the rotating conductive member, and a damping force is generated. Furthermore, each of the regions where the eddy current is generated generates heat. Therefore, the heat generation area | region of the number of permanent magnets is formed in a conductive member.

If the conductive member rotates in one direction at high speed, the heat generation region moves in the circumferential direction at high speed. Therefore, heat generation in the circumferential direction is made uniform, and no temperature difference occurs in the circumferential direction.

However, in the eddy current type damper used as a vibration damping device, the conductive member repeats forward rotation and reverse rotation to damp the vibration. That is, the rotation direction of the conductive member is repeatedly switched. The rotational speed of the conductive member becomes zero at the switching point of the rotational direction. This may cause the conductive member to rotate at extremely low speeds.

When the conductive member rotates at a very low speed, not only heat generating regions of the number of permanent magnets are formed in the conductive member, but also a low temperature region is formed between the heat generating regions. The thermal expansion of the heat generating area is constrained by the low temperature area where the thermal expansion is small. Therefore, distortion occurs in the heat generation area, and as a result, thermal stress is generated in the heat generation area. When the rotation at extremely low speed is repeated, thermal stress is repeatedly applied, causing fatigue damage to the conductive member.

In particular, in the eddy current type damper in which the rotational direction of the conductive member is repeatedly switched, the rotational speed of the conductive member in the circumferential direction necessarily changes due to its configuration, so heat generation in the circumferential direction of the conductive member is difficult to be uniform.

Further, in the eddy current type damper of Patent Document 2, since the guide nut is provided on the outside of the drum, dust easily intrudes between the guide nut and the ball screw. Further, in the eddy current damper of Patent Document 2, the guide nut is provided outside the drum, the flange portion of the guide nut is fixed to the drum, and the cylindrical portion of the guide nut extends toward the opposite side to the drum . Therefore, it is necessary to secure a long distance (stroke distance of the ball screw) between the end of the cylindrical portion of the guide nut opposite to the drum and the fixture fixed to the building, and the eddy current damper becomes large. Cheap. Furthermore, Patent Document 2 does not particularly mention a technique for managing the gap between the inner circumferential surface of the drum and the permanent magnet.

An object of the present invention is to provide an eddy current damper capable of suppressing fatigue damage to a conductive member in which an eddy current is generated. Another object of the present invention is to provide an eddy current damper which can be miniaturized.

The eddy current damper according to the present embodiment includes a screw shaft axially movable, a plurality of first permanent magnets arranged along the circumferential direction around the screw shaft, and the first permanent magnets. A plurality of second permanent magnets arranged with a gap between the first permanent magnet and a reversed arrangement of the first permanent magnet and the magnetic pole, and a cylindrical magnet holding member for holding the first permanent magnet and the second permanent magnet A conductive member having a cylindrical shape and facing the first permanent magnet and the second permanent magnet with a gap therebetween, a magnet holding member and a conductive member disposed inside and fixed to the magnet holding member or the conductive member And a heat transfer layer covering a surface facing the first permanent magnet and the second permanent magnet of the conductive member and having a thermal conductivity higher than that of the conductive member.

According to the eddy current damper of the present embodiment, it is possible to suppress the fatigue damage of the conductive member in which the eddy current is generated. Moreover, according to the eddy current damper of the present embodiment, downsizing can be achieved.

FIG. 1 is a cross-sectional view in a plane along an axial direction of the eddy current damper of the first embodiment. FIG. 2 is a partially enlarged view of FIG. FIG. 3 is a cross-sectional view in a plane perpendicular to the axial direction of the eddy current damper of the first embodiment. FIG. 4 is a partially enlarged view of FIG. FIG. 5 is a perspective view showing the first permanent magnet and the second permanent magnet of the first embodiment. FIG. 6 is a schematic view showing a magnetic circuit of the eddy current damper of the first embodiment. FIG. 7 is a perspective view showing a first permanent magnet and a second permanent magnet in which the arrangement of magnetic poles is in the circumferential direction. FIG. 8 is a schematic view showing a magnetic circuit of the eddy current damper of FIG. FIG. 9 is a perspective view showing a plurality of first permanent magnets and a plurality of second permanent magnets arranged in the axial direction. FIG. 10 is a cross-sectional view in a plane along the axial direction of the eddy current damper of the second embodiment. FIG. 11 is a cross-sectional view in a plane perpendicular to the axial direction of the eddy current damper of the second embodiment. FIG. 12 is a cross-sectional view of a surface of the eddy current damper of the third embodiment along the axial direction. FIG. 13 is a partially enlarged view of FIG. FIG. 14 is a cross-sectional view of a surface of the eddy current damper of the fourth embodiment along the axial direction.

The eddy current damper according to the present embodiment has a screw-shaped shaft movable in the axial direction, a plurality of first permanent magnets, a plurality of second permanent magnets, a cylindrical magnet holding member, and a cylindrical shape having conductivity. And a heat transfer layer covering a surface facing the first permanent magnet and the second permanent magnet of the conductive member. The first permanent magnets are arranged circumferentially around the screw axis. The second permanent magnet is disposed between the first permanent magnets with a gap from the first permanent magnet, and the arrangement of the first permanent magnet and the magnetic pole is reversed. The magnet holding member holds the first permanent magnet and the second permanent magnet. The conductive member opposes the first permanent magnet and the second permanent magnet with a gap. The ball nut is disposed inside the magnet holding member and the conductive member and fixed to the magnet holding member or the conductive member. The heat transfer layer has a higher thermal conductivity than the conductive member.

According to the eddy current damper of the present embodiment, when kinetic energy is given to the damper, the screw shaft moves in the axial direction. The axial movement of the screw shaft causes the ball nut to rotate. Thereby, the conductive member rotates relative to the first and second permanent magnets in the magnetic field generated by each of the first and second permanent magnets. At this time, eddy currents are generated in the regions of the surface of the conductive member facing the respective first and second permanent magnets. Thereby, a damping force is applied to the rotating conductive member, and a damping force is generated. Furthermore, each of the regions where the eddy current is generated generates heat.

Here, the surface of the conductive member facing the first and second permanent magnets is covered with a heat transfer layer having a thermal conductivity higher than that of the conductive member. Therefore, when the conductive member rotates at a very low speed relative to the first and second permanent magnets, the heat of the heat generating region generated in the conductive member is rapidly transmitted to the heat transfer layer, and further in the circumferential direction of the heat transfer layer. scatter. This can reduce the occurrence of a temperature difference in the circumferential direction of the conductive member. Therefore, the fatigue damage of the conductive member which an eddy current produces can be suppressed.

Further, according to the eddy current damper of the present embodiment, the ball nut is disposed inside the conductive member and the magnet holding member. Kinetic energy is given to the eddy current damper by vibration or the like, and the ball nut does not move in the axial direction even if the screw shaft moves in the axial direction. Therefore, it is not necessary to provide the movable region of the ball nut in the eddy current damper. Therefore, parts such as the magnet holding member and the conductive member can be made smaller. Thereby, downsizing of the eddy current damper can be realized. Moreover, weight reduction of the eddy current damper can be realized. Furthermore, since each component has a simple configuration, assembly of the eddy current damper is facilitated. Furthermore, the parts cost and manufacturing cost of the eddy current damper become low.

The above-described eddy current damper of the present embodiment can adopt any of the following configurations (1) to (4).

(1) The magnet holding member is disposed inside the conductive member. The first permanent magnet and the second permanent magnet are attached to the outer circumferential surface of the magnet holding member. A ball nut is fixed to the magnet holding member.

In this case, the inner circumferential surface of the conductive member faces the first and second permanent magnets with a gap. A heat transfer layer is formed on the inner circumferential surface of the conductive member. The axial movement of the screw shaft rotates the ball nut and the magnet holding member. On the other hand, the conductive member does not rotate. As a result, the magnetic flux passing through the conductive member from the first and second permanent magnets changes, and an eddy current is generated on the inner peripheral surface of the conductive member. A demagnetizing field is generated by the eddy current, and a reaction force (braking force) is applied to the rotating magnet holding member. As a result, the screw shaft receives a damping force.

Further, in this case, the conductive member is disposed outside the magnet holding member to be in contact with the outside air. Thereby, the conductive member is cooled by the outside air. As a result, the temperature rise of the conductive member can be suppressed.

(2) The conductive member is disposed inside the magnet holding member. The first permanent magnet and the second permanent magnet are attached to the inner circumferential surface of the magnet holding member. The ball nut is fixed to the conductive member.

In this case, the outer circumferential surface of the conductive member faces the first and second permanent magnets with a gap. A heat transfer layer is formed on the outer peripheral surface of the conductive member. The axial movement of the screw shaft rotates the ball nut and the conductive member. On the other hand, the magnet holding member does not rotate. As a result, the magnetic flux passing through the conductive member from the first and second permanent magnets changes, and an eddy current is generated on the outer peripheral surface of the conductive member. A demagnetizing field is generated by this eddy current, and a reaction force is given to the rotating conductive member. As a result, the screw shaft receives a damping force.

Further, in this case, the magnet holding member is disposed outside the conductive member and is in contact with the outside air. Thereby, the magnet holding member is cooled by the outside air. As a result, the temperature rise of the first and second permanent magnets can be suppressed.

(3) The magnet holding member is disposed inside the conductive member. The first permanent magnet and the second permanent magnet are attached to the outer circumferential surface of the magnet holding member. The ball nut is fixed to the conductive member.

In this case, the inner circumferential surface of the conductive member faces the first and second permanent magnets with a gap. A heat transfer layer is formed on the inner circumferential surface of the conductive member. The axial movement of the screw shaft rotates the ball nut and the conductive member. On the other hand, the magnet holding member does not rotate. As a result, the magnetic flux passing through the conductive member from the first and second permanent magnets changes, and an eddy current is generated on the inner peripheral surface of the conductive member. A demagnetizing field is generated by this eddy current, and a reaction force is given to the rotating conductive member. As a result, the screw shaft receives a damping force.

Further, in this case, the conductive member is disposed outside the magnet holding member to be in contact with the outside air. Thus, the rotating conductive member is efficiently cooled by the outside air. As a result, the temperature rise of the conductive member can be suppressed.

(4) The conductive member is disposed inside the magnet holding member. The first permanent magnet and the second permanent magnet are attached to the inner circumferential surface of the magnet holding member. A ball nut is fixed to the magnet holding member.

In this case, the outer circumferential surface of the conductive member faces the first and second permanent magnets with a gap. A heat transfer layer is formed on the outer peripheral surface of the conductive member. The axial movement of the screw shaft rotates the ball nut and the magnet holding member. On the other hand, the conductive member does not rotate. As a result, the magnetic flux passing through the conductive member from the first and second permanent magnets changes, and an eddy current is generated on the outer peripheral surface of the conductive member. A demagnetizing field is generated by this eddy current, and a reaction force is given to the rotating magnet holding member. As a result, the screw shaft receives a damping force.

Further, in this case, the magnet holding member is disposed outside the conductive member and is in contact with the outside air. Thus, the rotating magnet holding member is efficiently cooled by the outside air. As a result, the temperature rise of the first and second permanent magnets can be suppressed.

In the eddy current damper of the present embodiment, the material of the heat transfer layer is not limited as long as the heat transfer layer has a thermal conductivity higher than that of the conductive member. As a typical example, the heat transfer layer is a metal layer. As a method of forming a metal layer in a conductive member, plating, build-up welding, brazing, thermal spraying, thermal diffusion bonding, etc. may be mentioned. Of these methods, plating is preferred. This is because a metal layer (heat transfer layer) having a uniform thickness can be easily formed.

In the eddy current damper of the present embodiment, the heat transfer layer is preferably made of copper or a copper alloy. This is because the thermal conductivity of copper and copper alloys is extremely high.

When the heat transfer layer is made of copper or a copper alloy, the thickness of the heat transfer layer is preferably 0.6 mm or more. If the heat transfer layer of copper or copper alloy is 0.6 mm or more, the heat transmitted from the heat generation region of the conductive member to the heat transfer layer is effectively dispersed in the circumferential direction of the heat transfer layer. Preferably, the thickness of the heat transfer layer in this case is 0.8 mm or more.

In the eddy current damper of the present embodiment, the heat transfer layer may be made of aluminum or an aluminum alloy. The thermal conductivity of aluminum and aluminum alloys is not so high as that of copper and copper alloys, but is extremely high.

When the heat transfer layer is made of aluminum or an aluminum alloy, the thickness of the heat transfer layer is preferably 1.0 mm or more. If the heat transfer layer of aluminum or aluminum alloy is 1.0 mm or more, the heat transmitted from the heat generating region of the conductive member to the heat transfer layer is effectively dispersed in the circumferential direction of the heat transfer layer. Preferably, the thickness of the heat transfer layer in this case is 1.3 mm or more.

When the heat transfer layer is made of copper, a copper alloy, aluminum or an aluminum alloy, the thickness of the heat transfer layer is preferably 2.0 mm or less. This is due to the following reasons. Copper, copper alloys, aluminum and aluminum alloys are nonmagnetic materials. If the heat transfer layer made of such a material is too thick, the distance between the first and second permanent magnets and the conductive member increases, and the braking force decreases. Therefore, when the heat transfer layer is made of copper, copper alloy, aluminum or aluminum alloy, the thickness of the heat transfer layer is preferably 2.0 mm or less from the viewpoint of securing the damping force.

In the eddy current damper of the present embodiment, a plurality of first permanent magnets are disposed along the axial direction of the magnet holding member, and a plurality of second permanent magnets are disposed along the axial direction of the magnet holding member. It is also good.

In this case, even if the size of one first permanent magnet and one second permanent magnet is small, the total size of the plurality of first and second permanent magnets is large. Therefore, the cost of the first and second permanent magnets can be reduced while increasing the damping force of the eddy current damper. In addition, attachment of the first and second permanent magnets to the magnet holding member is easy.

Hereinafter, the eddy current damper of the present embodiment will be described with reference to the drawings.

First Embodiment
FIG. 1 is a cross-sectional view in a plane along an axial direction of the eddy current damper of the first embodiment. FIG. 2 is a partially enlarged view of FIG. Referring to FIGS. 1 and 2, the eddy current damper 1 includes a magnet holding member 2, a plurality of first permanent magnets 3, a plurality of second permanent magnets 4, a conductive member 5, and a ball nut 6. , Screw shaft 7 and heat transfer layer 12 (see FIG. 2).

Magnet holding member
The magnet holding member 2 includes a main cylinder 2A, a tip side sub cylinder 2B, and a root side sub cylinder 2C.

The main cylinder 2A has a cylindrical shape with the screw shaft 7 as a central axis. The axial length of the screw shaft 7 of the main cylinder 2A is longer than the axial length of the screw shaft 7 of the first permanent magnet 3 and the second permanent magnet 4.

The tip side sub-cylinder 2B extends from the end of the tip side of the main cylinder 2A (the free end side of the screw shaft 7 or the attachment 8a side). The tip side sub-cylinder 2B has a cylindrical shape with the screw shaft 7 as a central axis. The outer diameter of the front end side sub-cylinder 2B is smaller than the outer diameter of the main cylinder 2A.

The root side sub-cylinder 2C is provided on the root side (attachment 8b side) of the main cylinder 2A with the flange portion 6A of the ball nut interposed. The root side sub-cylinder 2C includes a flange fixing portion 21C and a cylindrical support portion 22C. The flange fixing portion 21C has a cylindrical shape with the screw shaft 7 as a central axis, and is fixed to the flange portion 6A of the ball nut. The cylindrical support portion 22C extends from the end of the root side (attachment 8b side) of the flange fixing portion 21C, and has a cylindrical shape. The outer diameter of the cylindrical support portion is smaller than the outer diameter of the flange fixing portion 21C.

The magnet holding member 2 of such a configuration can accommodate the cylindrical portion 6B of the ball nut 6 and a part of the screw shaft 7 inside. The material of the magnet holding member 2 is not particularly limited. However, the material of the magnet holding member 2 is preferably steel or the like having high permeability. The material of the magnet holding member 2 is, for example, a ferromagnetic material such as carbon steel or cast iron. In this case, the magnet holding member 2 plays a role as a yoke. That is, the magnetic flux from the first permanent magnet 3 and the second permanent magnet 4 hardly leaks to the outside, and the damping force of the eddy current damper 1 is increased. As described later, the magnet holding member 2 is rotatable with respect to the conductive member 5.

[First Permanent Magnet and Second Permanent Magnet]
FIG. 3 is a cross-sectional view in a plane perpendicular to the axial direction of the eddy current damper of the first embodiment. FIG. 4 is a partially enlarged view of FIG. FIG. 5 is a perspective view showing the first permanent magnet and the second permanent magnet of the first embodiment. In FIGS. 3 to 5, the configuration of part of the screw shaft and the like is omitted. Referring to FIGS. 3 to 5, the plurality of first permanent magnets 3 and the plurality of second permanent magnets 4 are attached to the outer peripheral surface of the magnet holding member 2 (main cylinder 2A). The first permanent magnet 3 is arranged around the screw axis (that is, along the circumferential direction of the magnet holding member 2). Similarly, the second permanent magnet 4 is arranged around the screw axis (that is, along the circumferential direction of the magnet holding member 2). The second permanent magnet 4 is disposed with a gap between the first permanent magnets 3. That is, the first permanent magnet 3 and the second permanent magnet 4 are alternately arranged with a gap along the circumferential direction of the magnet holding member 2.

The magnetic poles of the first permanent magnet 3 and the second permanent magnet 4 are disposed in the radial direction of the magnet holding member 2. The arrangement of the magnetic poles of the second permanent magnet 4 is opposite to the arrangement of the magnetic poles of the first permanent magnet 3. For example, referring to FIGS. 4 and 5, in the radial direction of magnet holding member 2, the N pole of first permanent magnet 3 is disposed outside, and the S pole thereof is disposed inside. Therefore, the south pole of the first permanent magnet 3 is in contact with the magnet holding member 2. On the other hand, in the radial direction of the magnet holding member 2, the N pole of the second permanent magnet 4 is disposed inside, and the S pole thereof is disposed outside. Therefore, the N pole of the second permanent magnet 4 contacts the magnet holding member 2.

Preferably, the size and nature of the second permanent magnet 4 are the same as the size and nature of the first permanent magnet 3. The first permanent magnet 3 and the second permanent magnet 4 are fixed to the magnet holding member 2 by an adhesive, for example. Of course, not only the adhesive but also the first permanent magnet 3 and the second permanent magnet 4 may be fixed by screws or the like.

[Conductive member]
Referring to FIGS. 1 and 2, conductive member 5 includes a central cylindrical portion 5A, a distal end side conical portion 5B, a distal end side cylindrical portion 5C, a root side conical portion 5D, and a root side cylindrical portion 5E. .

The central cylindrical portion 5A has a cylindrical shape with the screw shaft 7 as a central axis. The inner circumferential surface of the central cylindrical portion 5A faces the first permanent magnet 3 and the second permanent magnet 4 with a gap. The distance between the inner peripheral surface of the central cylindrical portion 5A and the first permanent magnet 3 (or the second permanent magnet 4) is constant along the axial direction of the screw shaft 7. The axial length of the screw shaft 7 of the central cylindrical portion 5A is longer than the axial length of the screw shaft 7 of the first permanent magnet 3 and the second permanent magnet 4.

The tip side conical portion 5B has a conical shape with the screw shaft 7 as a central axis. The tip side conical portion 5B extends from the end of the central cylindrical portion 5A on the tip end side (the free end side of the screw shaft 7 or the attachment 8a side), and on the tip end side (the free end side of the screw shaft 7 or the attachment 8a side) The outer diameter and the inner diameter decrease as heading.

The front end side cylindrical portion 5C has a cylindrical shape with the screw shaft 7 as a central axis. The distal end side cylindrical portion 5C extends from the end of the distal end side (the free end side of the screw shaft 7 or the attachment 8a side) of the distal end side conical portion 5B. The end of the tip end side (the free end side of the screw shaft 7 or the attachment 8a side) of the tip end side cylindrical portion 5C is fixed to the attachment 8a.

The root side conical portion 5D has a conical shape with the screw shaft 7 as a central axis. The root side conical portion 5D extends from the end of the central cylindrical portion 5A on the root side (attachment 8b side), and the outer diameter and the inner diameter decrease toward the root side (attachment 8b side).

The root side cylindrical portion 5E has a cylindrical shape with the screw shaft 7 as a central axis. The root side cylindrical portion 5E extends from the end of the root side (fitting 8b side) of the root side conical portion 5D. The end on the root side (attachment 8b side) of the root side cylindrical portion 5E is a free end.

The conductive member 5 having such a configuration can accommodate the magnet holding member 2, the first permanent magnet 3, the second permanent magnet 4, the ball nut 6, and part of the screw shaft 7. That is, the magnet holding member 2 is concentrically disposed inside the conductive member 5. As described later, the conductive member 5 rotates relative to the magnet holding member 2 in order to generate an eddy current on the inner peripheral surface of the conductive member 5 (the inner peripheral surface of the central cylindrical portion 5A). Therefore, a gap is provided between the conductive member 5 and the first permanent magnet 3 and the second permanent magnet 4. The fixture 8a integral with the conductive member 5 is fixed in the building support surface or in the building. Therefore, the conductive member 5 does not rotate around the screw shaft 7.

The conductive member 5 has conductivity. The material of the conductive member 5 is, for example, a ferromagnetic material such as carbon steel or cast iron.

The conductive member 5 rotatably supports the magnet holding member 2. For example, the support of the magnet holding member 2 is preferably configured as follows.

Referring to FIG. 1, the eddy current damper 1 further includes a tip end bearing 9A and a root side bearing 9B. The tip end side bearing 9A is a conductive member 5 (tip end side cylindrical portion 5C) on the tip end side of the screw shaft 7 (the free end side of the screw shaft 7 or the attachment 8a side) than the first permanent magnet 3 and the second permanent magnet 4 And the outer peripheral surface of the magnet holding member 2 (tip side sub cylinder 2B). Further, the root side bearing 9B is on the inner peripheral surface of the conductive member 5 (root side cylindrical portion 5E) on the root side (attachment 8b side) of the screw shaft 7 than the first permanent magnet 3 and the second permanent magnet 4 It is attached and supports the outer peripheral surface of the magnet holding member 2 (cylindrical support 22C).

With such a configuration, the magnet holding member 2 is supported on both sides of the first permanent magnet 3 and the second permanent magnet 4 in the axial direction of the screw shaft 7. Therefore, even if the magnet holding member 2 rotates, the gap between the first permanent magnet 3 (the second permanent magnet 4) and the conductive member 5 is likely to be maintained at a constant distance. If the gap is kept at a fixed distance, the braking force by the eddy current can be stably obtained. Further, if the gap is kept at a constant distance, the possibility of the first permanent magnet 3 and the second permanent magnet 4 coming into contact with the conductive member 5 is low, so the gap can be further reduced. Then, as described later, the amount of magnetic flux from the first permanent magnet 3 and the second permanent magnet 4 passing through the conductive member 5 increases, and the braking force can be further increased, or the number of permanent magnets can be reduced. Can also exert a desired braking force.

A thrust bearing 10 is provided between the magnet holding member 2 and the conductive member 5 in the axial direction of the magnet holding member 2. The types of the tip side bearing 9A, the root side bearing 9B and the thrust bearing 10 are not particularly limited, and it is a matter of course that a ball type, a roller type, a sliding type or the like may be used.

The central cylindrical portion 5A, the distal end side conical portion 5B, the distal end side cylindrical portion 5C, the root side conical portion 5D and the root side cylindrical portion 5E are separate members, and are connected and assembled by bolts or the like.

Referring to FIGS. 2 and 4, the inner circumferential surface of the conductive member 5 is a surface facing the plurality of first permanent magnets 3 and the second permanent magnets 4. The heat transfer layer 12 is formed on the inner peripheral surface of the conductive member 5. The heat transfer layer 12 of the present embodiment is a metal layer of copper or a copper alloy formed by plating. The thermal conductivity of the heat transfer layer 12 is higher than the thermal conductivity of the conductive member 5.

[Ball nut]
The ball nut 6 includes a flange portion 6A and a cylindrical portion 6B. The flange portion 6A has a cylindrical shape. The flange portion 6A is between the end of the root side (attachment 8b side) of the main cylinder 2A of the magnet holding member and the end of the tip end side (attachment 8a side) of the flange fixing portion 21C of the root side sub cylinder 2C. It is provided and fixed to both. The cylindrical portion 6B is provided on the tip end side of the screw shaft 7 more than the flange portion 6A, and extends from the surface on the tip end side of the flange portion 6A.

The ball nut 6 having such a configuration is disposed inside the magnet holding member 2 and the conductive member 5. Since the ball nut 6 is fixed to the magnet holding member 2, when the ball nut 6 rotates, the magnet holding member 2 also rotates. The type of ball nut 6 is not particularly limited. The ball nut 6 may use a well-known ball nut. A threaded portion is formed on the inner circumferential surface of the ball nut 6. In addition, in FIG. 1, drawing of a part of cylindrical part 6B of the ball nut 6 is abbreviate | omitted, and the screw shaft 7 is made to be visible.

[Screw shaft]
The screw shaft 7 penetrates the ball nut 6 and engages with the ball nut 6 through the ball. On the outer peripheral surface of the screw shaft 7, a screw portion corresponding to the screw portion of the ball nut 6 is formed. The screw shaft 7 and the ball nut 6 constitute a ball screw. The ball screw converts the axial movement of the screw shaft 7 into the rotational movement of the ball nut 6. The fixture 8 b is connected to the screw shaft 7. The fixture 8b integral with the screw shaft 7 is fixed in the building support surface or in the building. In the case where the eddy current damper 1 is installed, for example, in the seismic isolation layer between the inside of a building and a building support surface, the fixture 8b integral with the screw shaft 7 is fixed in the building and integrated with the conductive member 5 The fixture 8a is fixed to the building support surface. In the case where the eddy current type damper 1 is installed, for example, in any layer in a building, the fixture 8b integral with the screw shaft 7 is fixed to the upper beam side of any layer and integrated with the conductive member 5 The fixture 8a is fixed to the lower beam side between arbitrary layers. Therefore, the screw shaft 7 does not rotate around the axis.

Fixing of the fixture 8b integral with the screw shaft 7 and the fixture 8a integral with the conductive member 5 may be reversed to the above description. That is, the fixture 8b integral with the screw shaft 7 may be fixed to the building support surface, and the fixture 8a integral with the conductive member 5 may be fixed within the building.

The screw shaft 7 is movable axially forward and backward inside the magnet holding member 2 and the conductive member 5. Therefore, when kinetic energy is given to the eddy current damper 1 by vibration or the like, the screw shaft 7 moves in the axial direction. When the screw shaft 7 moves in the axial direction, the ball nut 6 rotates around the screw shaft 7 by the action of the ball screw. As the ball nut 6 rotates, the magnet holding member 2 rotates. As a result, since the first permanent magnet 3 and the second permanent magnet 4 integral with the magnet holding member 2 rotate relative to the conductive member 5, an eddy current is generated in the conductive member 5. As a result, a damping force is generated in the eddy current damper 1 to damp the vibration.

According to the eddy current damper 1 of the present embodiment, the heat transfer layer in which the inner peripheral surface of the conductive member 5 facing the first permanent magnet 3 and the second permanent magnet 4 has a thermal conductivity higher than that of the conductive member 5 Covered with twelve. Therefore, when the conductive member 5 rotates at a very low speed relative to the first permanent magnet 3 and the second permanent magnet 4, the heat of the heat generating region generated in the conductive member 5 is rapidly transmitted to the heat transfer layer 12 and further It disperses in the circumferential direction of the heat transfer layer 12. Thereby, generation of a temperature difference in the circumferential direction of the conductive member 5 can be reduced. Therefore, the fatigue damage of the conductive member 5 which an eddy current produces can be suppressed.

Further, according to the eddy current damper 1 of the present embodiment, the ball nut 6 is disposed inside the conductive member 5 and the magnet holding member 2. Kinetic energy is given to the eddy current damper 1 by vibration or the like, and the ball nut 6 does not move in the axial direction even if the screw shaft 7 integral with the fixture 8 b moves in the axial direction. Therefore, it is not necessary to provide the eddy current damper 1 with the movable region of the ball nut 6. Therefore, parts such as the magnet holding member 2 and the conductive member 5 can be made smaller. Thereby, the eddy current damper 1 can be miniaturized, and the weight reduction of the eddy current damper 1 can be realized.

In addition, the ball nut 6 is disposed inside the conductive member 5 and the magnet holding member 2 so that dust does not easily enter between the ball nut 6 and the screw shaft 7, and the screw shaft 7 becomes smooth over a long period of time. It can move. Further, by arranging the ball nut 6 inside the conductive member 5 and the magnet holding member 2, the end of the tip end side (attachment 8a side) of the fixture 8b and the root side of the conductive member 5 (attachment 8b side) It is possible to shorten the distance to the end of the coil and to miniaturize the eddy current damper. Moreover, since each component is a simple structure, the assembly of the eddy current type damper 1 becomes easy. In addition, parts cost and manufacturing cost of the eddy current damper 1 become low.

In addition, the conductive member 5 accommodates the first permanent magnet 3 and the second permanent magnet 4 therein. That is, the axial length of the screw shaft 7 of the conductive member 5 is longer than the axial length of the screw shaft 7 of the first permanent magnet 3 (second permanent magnet 4), and the volume of the conductive member 5 is large. As the volume of the conductive member 5 increases, the heat capacity of the conductive member 5 also increases. Therefore, the temperature rise of the electrically-conductive member 5 by generation | occurrence | production of an eddy current is suppressed. If the temperature rise of the conductive member 5 is suppressed, the temperature rise of the first permanent magnet 3 and the second permanent magnet 4 due to the radiant heat from the conductive member 5 is suppressed, and the temperatures of the first permanent magnet 3 and the second permanent magnet 4 Demagnetization due to the rise is suppressed.

Subsequently, the generation principle of the eddy current and the generation principle of the damping force by the eddy current will be described.

[Attenuation force due to eddy current]
FIG. 6 is a schematic view showing a magnetic circuit of the eddy current damper. Referring to FIG. 6, the arrangement of the magnetic poles of the first permanent magnet 3 is opposite to the arrangement of the magnetic poles of the adjacent second permanent magnet 4. Therefore, the magnetic flux emitted from the N pole of the first permanent magnet 3 reaches the S pole of the adjacent second permanent magnet 4. The magnetic flux emitted from the N pole of the second permanent magnet reaches the S pole of the adjacent first permanent magnet 3. Thus, a magnetic circuit is formed among the first permanent magnet 3, the second permanent magnet 4, the conductive member 5 and the magnet holding member 2. Since the gap between the first and second

permanent magnets

3 and 4 and the conductive member 5 is sufficiently small, the conductive member 5 is in the magnetic field.

When the magnet holding member 2 rotates (see the arrow in FIG. 6), the first permanent magnet 3 and the second permanent magnet 4 move relative to the conductive member 5. Therefore, the magnetic flux passing through the surface of the conductive member 5 (the inner peripheral surface of the conductive member 5 opposed to the first permanent magnet 3 and the second permanent magnet 4 in FIG. 6) changes. As a result, an eddy current is generated on the surface of the conductive member 5 (the inner peripheral surface of the conductive member 5 in FIG. 6). When an eddy current is generated, a new magnetic flux (demagnetizing field) is generated. The new magnetic flux prevents relative rotation between the magnet holding member 2 (the first permanent magnet 3 and the second permanent magnet 4) and the conductive member 5. In the case of this embodiment, the rotation of the magnet holding member 2 is prevented. If rotation of the magnet holding member 2 is prevented, rotation of the ball nut 6 integral with the magnet holding member 2 is also prevented. If the rotation of the ball nut 6 is blocked, the axial movement of the screw shaft 7 is also blocked. This is the damping force of the eddy current damper 1. An eddy current generated by kinetic energy due to vibration or the like raises the temperature of the conductive member 5. That is, kinetic energy given to the eddy current damper is converted to thermal energy to obtain a damping force.

According to the eddy current damper of the present embodiment, the arrangement of the magnetic poles of the first permanent magnet is reversed to the arrangement of the magnetic poles of the second permanent magnet adjacent to the first permanent magnet in the circumferential direction of the magnet holding member . Therefore, a magnetic field due to the first permanent magnet and the second permanent magnet is generated in the circumferential direction of the magnet holding member. Further, by arranging a plurality of first permanent magnets and second permanent magnets in the circumferential direction of the magnet holding member, the amount of magnetic flux reaching the conductive member is increased. As a result, the eddy current generated in the conductive member is increased, and the damping force of the eddy current damper is increased.

[Pole arrangement]
In the above description, the arrangement of the magnetic poles of the first permanent magnet and the second permanent magnet has been described in the case of the radial direction of the magnet holding member. However, the arrangement of the magnetic poles of the first permanent magnet and the second permanent magnet is not limited to this.

FIG. 7 is a perspective view showing a first permanent magnet and a second permanent magnet in which the arrangement of magnetic poles is in the circumferential direction. Referring to FIG. 7, the arrangement of the magnetic poles of the first permanent magnet 3 and the second permanent magnet 4 is along the circumferential direction of the magnet holding member 2. Even in this case, the arrangement of the magnetic poles of the first permanent magnet 3 is opposite to the arrangement of the magnetic poles of the second permanent magnet 4. A ferromagnetic polepiece 11 is provided between the first permanent magnet 3 and the second permanent magnet 4.

FIG. 8 is a schematic view showing a magnetic circuit of the eddy current damper of FIG. Referring to FIG. 8, the magnetic flux emitted from the N pole of first permanent magnet 3 passes through pole piece 11 to reach the S pole of first permanent magnet 3. The same applies to the second permanent magnet 4. Thus, a magnetic circuit is formed among the first permanent magnet 3, the second permanent magnet 4, the pole piece 11 and the conductive member 5. Thus, the damping force is obtained in the eddy current damper 1 as described above.

[Arrangement of permanent magnet in axial direction]
In order to increase the damping force of the eddy current damper 1, the eddy current generated in the conductive member may be increased. One way to generate large eddy currents is to increase the amount of magnetic flux exiting the first and second permanent magnets. That is, the sizes of the first permanent magnet and the second permanent magnet may be increased. However, the large-sized first permanent magnet and the second permanent magnet are expensive, and their attachment to the magnet holding member is not easy.

FIG. 9 is a perspective view showing a plurality of first permanent magnets and a plurality of second permanent magnets arranged in the axial direction. Referring to FIG. 9, a plurality of first permanent magnets 3 and second permanent magnets 4 may be arranged in the axial direction of one magnet holding member 2. Thereby, the size of each of the one first permanent magnet 3 and the one second permanent magnet 4 may be small. On the other hand, the total size of the plurality of first permanent magnets 3 and the second permanent magnets 4 attached to the magnet holding member 2 is large. Therefore, the cost of the first permanent magnet 3 and the second permanent magnet 4 can be reduced. Moreover, attachment to the magnet holding member 2 of the 1st permanent magnet 3 and the 2nd permanent magnet 4 is also easy.

The circumferential arrangement of the magnet holding member 2 of the axially arranged first and second

permanent magnets

3 and 4 is the same as described above. That is, the first permanent magnets 3 and the second permanent magnets 4 are alternately arranged along the circumferential direction of the magnet holding member 2.

In order to increase the damping force of the eddy current damper 1, the first permanent magnet 3 is preferably adjacent to the second permanent magnet 4 in the axial direction of the magnet holding member 2. In this case, the magnetic circuit is generated not only in the circumferential direction of the magnet holding member 2 but also in the axial direction. Therefore, the eddy current generated in the conductive member 5 is increased. As a result, the damping force of the eddy current damper 1 is increased.

However, the arrangement of the first permanent magnet 3 and the second permanent magnet 4 in the axial direction of the magnet holding member 2 is not particularly limited. That is, in the axial direction of the magnet holding member 2, the first permanent magnet 3 may be disposed adjacent to the first permanent magnet 3 or may be disposed adjacent to the second permanent magnet 4.

In the first embodiment described above, the case where the magnet holding member is disposed inside the conductive member, the first permanent magnet and the second permanent magnet are attached to the outer peripheral surface of the magnet holding member, and the magnet holding member rotates further did. However, the eddy current damper of the present embodiment is not limited to this.

Second Embodiment
In the eddy current damper of the second embodiment, the magnet holding member is disposed outside the conductive member and does not rotate. Eddy current is generated by rotation of the inner conductive member. In the eddy current damper of the second embodiment, the arrangement relationship between the magnet holding member and the conductive member is reverse to that of the first embodiment. However, the shape of the magnet holding member of the second embodiment is the same as the conductive member of the first embodiment, and the shape of the conductive member of the second embodiment is the same as the magnet holding member of the first embodiment. Therefore, in the second embodiment, the description of the detailed shapes of the magnet holding member and the conductive member is omitted.

FIG. 10 is a cross-sectional view in a plane along the axial direction of the eddy current damper of the second embodiment. FIG. 11 is a cross-sectional view in a plane perpendicular to the axial direction of the eddy current damper of the second embodiment. Referring to FIGS. 10 and 11, magnet holding member 2 can accommodate conductive member 5, ball nut 6 and screw shaft 7. The first permanent magnet 3 and the second permanent magnet 4 are attached to the inner peripheral surface of the magnet holding member 2. Therefore, the outer peripheral surface of the conductive member 5 faces the first permanent magnet 3 and the second permanent magnet 4 with a gap. The heat transfer layer 12 is formed on the outer peripheral surface of the conductive member 5.

The fixture 8 a shown in FIG. 1 is connected to the magnet holding member 2. Therefore, the magnet holding member 2 does not rotate around the screw shaft 7. On the other hand, the ball nut 6 is connected to the conductive member 5. Therefore, when the ball nut 6 rotates, the conductive member 5 rotates. Even in such a configuration, as described above, since the first permanent magnet 3 and the second permanent magnet 4 integral with the magnet holding member 2 rotate relative to the conductive member 5, an eddy current is generated in the conductive member 5 Occurs. As a result, a damping force is generated in the eddy current damper 1 to damp the vibration.

Third Embodiment
In the eddy current damper of the third embodiment, the magnet holding member is disposed inside the conductive member and does not rotate. An eddy current is generated by rotation of the outer conductive member.

FIG. 12 is a cross-sectional view of a surface of the eddy current damper of the third embodiment along the axial direction. FIG. 13 is a partially enlarged view of FIG. Referring to FIGS. 12 and 13, the conductive member 5 can accommodate the magnet holding member 2, the ball nut 6, and the screw shaft 7. The first permanent magnet 3 and the second permanent magnet 4 are attached to the outer peripheral surface of the magnet holding member 2. Therefore, the inner circumferential surface of the conductive member 5 faces the first permanent magnet 3 and the second permanent magnet 4 with a gap. The heat transfer layer 12 is formed on the inner peripheral surface of the conductive member 5.

The fixture 8 a is connected to the magnet holding member 2. Therefore, the magnet holding member 2 does not rotate around the screw shaft 7. On the other hand, the ball nut 6 is connected to the conductive member 5. Therefore, when the ball nut 6 rotates, the conductive member 5 rotates. Even in such a configuration, as described above, since the first permanent magnet 3 and the second permanent magnet 4 integral with the magnet holding member 2 rotate relative to the conductive member 5, an eddy current is generated in the conductive member 5 Occurs. As a result, a damping force is generated in the eddy current damper 1 to damp the vibration.

Fourth Embodiment
In the eddy current damper of the fourth embodiment, the conductive member is disposed inside the magnet holding member and does not rotate. Eddy current is generated by rotation of the outer magnet holding member.

FIG. 14 is a cross-sectional view of a surface of the eddy current damper of the fourth embodiment along the axial direction. Referring to FIG. 14, magnet holding member 2 can accommodate conductive member 5, ball nut 6 and screw shaft 7. The first permanent magnet 3 and the second permanent magnet 4 are attached to the inner peripheral surface of the magnet holding member 2. Therefore, the outer peripheral surface of the conductive member 5 faces the first permanent magnet 3 and the second permanent magnet 4 with a gap. The heat transfer layer 12 is formed on the outer peripheral surface of the conductive member 5.

The fixture 8 a shown in FIG. 1 is connected to the conductive member 5. Therefore, the conductive member 5 does not rotate around the screw shaft 7. On the other hand, the ball nut 6 is fixed to the magnet holding member 2. Therefore, when the ball nut 6 rotates, the magnet holding member 2 rotates. Even in such a configuration, as described above, since the first permanent magnet 3 and the second permanent magnet 4 integral with the magnet holding member 2 rotate relative to the conductive member 5, an eddy current is generated in the conductive member 5 Occurs. As a result, a damping force is generated in the eddy current damper 1 to damp the vibration.

As described above, when the eddy current damper generates a damping force, the temperature of the conductive member rises. The first permanent magnet and the second permanent magnet face the conductive member. Therefore, the temperatures of the first permanent magnet and the second permanent magnet may increase due to radiant heat from the conductive member and the heat transfer layer. If the temperature of the permanent magnet is increased, the magnetic force may be reduced.

In the eddy current damper of the first embodiment, the conductive member 5 is disposed outside the magnet holding member 2. That is, the conductive member 5 is disposed at the outermost side to be in contact with the outside air. Thereby, the conductive member 5 is cooled by the outside air. Therefore, the temperature rise of the conductive member 5 can be suppressed. As a result, temperature rise of the first permanent magnet and the second permanent magnet can be suppressed.

In the eddy current damper of the second embodiment, the magnet holding member 2 is disposed outside the conductive member 5. That is, the magnet holding member 2 is disposed at the outermost side to be in contact with the outside air. Thereby, the magnet holding member 2 is cooled by external air. Therefore, the first permanent magnet and the second permanent magnet can be cooled through the magnet holding member 2. As a result, temperature rise of the first permanent magnet and the second permanent magnet can be suppressed.

In the eddy current damper of the third embodiment, the conductive member 5 is disposed outside the magnet holding member 2. That is, the conductive member 5 is disposed at the outermost side to be in contact with the outside air. In addition, the conductive member 5 rotates around the screw shaft 7. Thus, the rotating conductive member 5 is efficiently cooled by the outside air. Therefore, the temperature rise of the conductive member 5 can be suppressed. As a result, temperature rise of the first permanent magnet and the second permanent magnet can be suppressed.

In the eddy current damper of the fourth embodiment, the magnet holding member 2 is disposed outside the conductive member 5. That is, the magnet holding member 2 is disposed at the outermost side to be in contact with the outside air. In addition, the magnet holding member 2 rotates around the screw shaft 7. Thereby, the rotating magnet holding member 2 is efficiently cooled by the outside air. Therefore, the first permanent magnet and the second permanent magnet can be cooled through the magnet holding member 2. As a result, the temperature rise of the first permanent magnet 3 and the second permanent magnet 4 can be suppressed.

The eddy current damper of the present embodiment has been described above. Since the eddy current is generated by the change of the magnetic flux passing through the conductive member 5, the first permanent magnet 3 and the second permanent magnet 4 may rotate relative to the conductive member 5. Further, as long as the conductive member 5 is present in the magnetic field generated by the first permanent magnet 3 and the second permanent magnet 4, the positional relationship between the conductive member and the magnet holding member is not particularly limited.

In addition, it goes without saying that the present invention is not limited to the above embodiment, and various modifications can be made without departing from the scope of the present invention.

The eddy current damper of the present invention is useful for a damping device and a seismic isolation device for a building.

1: Eddy current type damper 2: Magnet holding member 3: First permanent magnet 4: Second permanent magnet 5: Conductive member 6: Ball nut 7:

Screw shaft

8a, 8b: Fittings 9: Radial bearing 10: Thrust bearing 11 : Pole piece 12: Heat transfer layer

Claims

An axially movable screw shaft,
A plurality of first permanent magnets arranged circumferentially around the screw shaft;
A plurality of second permanent magnets disposed between the first permanent magnets with a gap from the first permanent magnet, wherein the arrangement of the first permanent magnet and the magnetic pole is reversed;
A cylindrical magnet holding member for holding the first permanent magnet and the second permanent magnet;
A cylindrical conductive member having conductivity and facing the first permanent magnet and the second permanent magnet with a gap in between;
A ball nut disposed inside the magnet holding member and the conductive member, fixed to the magnet holding member or the conductive member, and engaged with the screw shaft;
An eddy current damper, comprising: a heat transfer layer covering a surface facing the first permanent magnet and the second permanent magnet of the conductive member and having a thermal conductivity higher than that of the conductive member.
An eddy current damper according to claim 1, wherein
An eddy current damper, wherein the heat transfer layer is made of copper or a copper alloy.
An eddy current damper according to claim 2, wherein
An eddy current damper, wherein a thickness of the heat transfer layer is 0.6 mm or more.
An eddy current damper according to claim 1, wherein
An eddy current damper, wherein the heat transfer layer is made of aluminum or an aluminum alloy.
An eddy current damper according to claim 4, wherein
An eddy current damper, wherein the heat transfer layer has a thickness of 1.0 mm or more.
An eddy current damper according to any one of claims 2 to 5, wherein
An eddy current damper, wherein the heat transfer layer has a thickness of 2.0 mm or less.